METAL STEM & Threaded bowl
Not a common variant of the Viking and I have yet to establish where it comes chronologically in the Viking family.
The 'PAT.PEND.'lettering would indicate that this was an early attempt at a new system. As yet I have yet to find one that has not got the 'PAT.PEND.' wording, so it is possible it was discontinued before a patent was issued
The right hand part of image two shows the two smoke holes, which appear to merge into one at the mouthpiece end of the stem. Takes all the usual Viking bowls.
As with most Vikings, the silvering has mostly flaked off my example